Error: `std.uni.isUpper` conflicts with `std.ascii.isUpper`

[WebFreak001]

On Wednesday, 15 July 2020 at 11:25:34 UTC, aberba wrote:
> On Wednesday, 15 July 2020 at 07:01:34 UTC, WebFreak001 wrote:
>> On Tuesday, 14 July 2020 at 20:37:53 UTC, Marcone wrote:
>>> [...]
>>
>> Additionally to the other answers telling you how to fix it, 
>> it's important to know why it happens in the first place:
>>
>> [...]
>
> Without reading this very explanation, how would one know 
> whilst reading docs?

in that explanation I broadly covered:

https://dlang.org/spec/module.html#name_lookup
https://dlang.org/spec/module.html#selective_imports
https://dlang.org/phobos/std_ascii.html
https://dlang.org/phobos/std_ascii.html#isUpper
https://dlang.org/phobos/std_uni.html
https://dlang.org/phobos/std_uni.html#isUpper
https://dlang.org/phobos/std_uni.html#Character